The present invention relates to a photo-responsive conductive polymer and the processes of making the same, and particularly to a copolymerization of the 3-substituted thiophene monomers containing photo-responsive group with 3-substituted thiophene monomers.
Conventionally, the conductivity of a conjugated conductive polymer is about 10.sup.-12 -10.sup.-9 s/cm before doping and about 10.sup.0 -10.sup.5 s/cm after doping. Most of the conductive polymers can not be dissolved in organic solvents or melt-processed due to the rigid conjugated bond. Therefore, the polymers should be introduced with flexible side chains such as long alkyl groups to make the polymer soluble in organic solvents and melt-processable. On the other hand, in order to control the conductivity of the polymers by external stimulation, a photo-responsive functional group should be introduced into the polymers.
However, there is no disclosure related to a conductive polymer with photo-chemically induced property. In the related organic compound, only the Japan National Industrial Chemistry Laboratory discloses the synthesis of an azobenzene group containing 7,7,8,8-tetracyanoquinodimethane (TCNQ) derivatives and the making of a Langmuir-Blodget film which can change its conductivity when irradiated with ultra-violet light; the variation range is about 35%. But the entire preparation process is so complicated. Furthermore, the film has poor mechanical strength due to its low molecular weight, and can be easily fractured.